&nbsp&nbsp I am a
Reader in Astronomy in the Extragalactic
Astronomy group of the Department of Physics at Durham University. My research
concentrates on clusters of galaxies from an X-ray prespective.
Selecting clusters on the basis of their X-ray luminosity ensures
that the objects are massive and well-relaxed. In many cases these
clusters are relatively dense in their cores and the resulting
strong X-ray emission causes all the thermal energy of the gas
to be radiated away. This phenomenon is termed a "Cooling Flow".
The clear and unescapable conclusion from the X-ray observations
is that there is a substantial mass of gas that has cooled
but relatively little of this 'sink' had been found before 2000.

&nbsp&nbsp A color Hubble Space Telescope
ACS image of the central galaxy in A2390. This central galaxy contains
significant star formation.
We have had a series of HST
SNAPSHOT programs to determine the detailed
optical mophology of a complete sample of high optical line luminosity
systems and a control sample of optically dull central galaxies
(see HST Programs 8301
and 8719).
In total over 250 snapshots have or will soon be taken.

&nbsp&nbsp Results have found that the cores of clusters have considerable
masses of molecular gas and dust present. Work on
IRAM and JCMT
by myself has lead to the discovery of 17 central cluster
galaxies with CO(1-0) detections (click on icon for A1068). These CO line detections
imply 10^9--11.5 Msun of molecular gas at temperatures of 20-50K. We have also found
a large number of similar galaxies with strong H2 vibration-rotation lines in the
near-infrared from UKIRT observations. These observations indicate that there is
an underlying correlation between the ionised gas (Balmer lines) and molecular
gas (H2 and CO). We have since obtained more IRAM 30m observations of another
80 clusters resulting in over 50 CO detections, OVRO and PdBI interferometic
imaging and most recently Herschel spectroscopy of 11 BCGs.